Bladder cancer is one of the most common malignant tumors of the urinary system, particularly challenging to treat in advanced cases. Although multiple guidelines recommend immune checkpoint inhibitors (ICIs) for advanced bladder cancer, clinical trials show that only a subset of patients respond to this therapy, while the majority face significant immune resistance. Therefore, investigating the molecular mechanisms behind tumor-adaptive immune checkpoint targeting to elucidate the root cause of resistance is an urgent scientific problem.

An immune-resistant bladder cancer allograft mouse model was developed by serially implanting bladder cancer cells in situ and treating them with anti-PD-L1 antibody to induce resistance. In this generated immune-resistant model, single-cell RNA sequencing (scRNA-seq), genomic analysis, and tumor immune microenvironment (TME) characterization were used to identify the key gene, KLHDC7A. Through multi-omics analysis and in vivo and in vitro experiments—including lentivirus-mediated gene knockdown—the role and molecular mechanism of KLHDC7A in reshaping the bladder cancer immune microenvironment were investigated.

The study showed that anti-PD-L1-resistant tumors in immunocompetent mice grew over ten times faster than their original counterparts, whereas no significant change was observed in immunodeficient mice, indicating that anti-PD-L1 resistance is closely associated with immune status. Characteristics of resistant tumors included reduced cytotoxic transformation of exhausted CD8+ T cells and decreased immune rejection within tumors. Mechanistically, KLHDC7A in tumor cells acts as a key molecular bridge that promotes the binding of PPARγ with p300/CBP, significantly enhancing the acetylation of PPARγ by p300/CBP, thereby inhibiting NF-κB pathway activation and reducing CXCL9 secretion. Reduced CXCL9 further suppresses CD8+ T cell infiltration and cytotoxicity, ultimately contributing to immune resistance. Knockdown of KLHDC7A converted the immune-suppressive TME to a stimulatory TME, rendering the primary bladder cancer model re-sensitized to anti-PD-L1 therapy. Additionally, high baseline KLHDC7A expression levels were significantly associated with poor survival outcomes in patients undergoing anti-PD-(L)1 therapy across multiple cancer types.

This study reveals that KLHDC7A mediates immune suppression in the TME of bladder cancer through interaction with PPARγ and p300/CBP, which inhibits CD8+ T cell infiltration and anti-tumor activity, allowing bladder cancer cells to evade immune checkpoint-targeted therapy. This adaptive transcriptional mechanism clarifies the molecular basis of immune resistance in bladder cancer and suggests that KLHDC7A could serve as a novel therapeutic target in bladder cancer immunotherapy.